Geochemical characteristics of rare earth elements in surface sediments from Huainan coal mining subsidence area, Anhui Province, China

Rare earth elements(REEs) are widely used in environmental geochemical analysis process research due to their unique chemical characteristics. This study investigated the geochemical characteristics of rare earth elements in surface sediment from the Huainan coal mining subsidence area, Anhui Province, China. Twelve surface sediment samples were collected from Panyi, Guqiao and Xieqiao subsidence areas in the study area. The content of rare earth elements in the samples was tested and analyzed by ICP-MS, and the distribution characteristics and controlling factors of REEs and its material sources were discussed. The results show that the rare earth element content in the surface sediments is 54.63-130.45 μg/g, with an average of 102.6 μg/g. The ratio of LREE/HREE varies from 11.89 to 20.55, with an average value of 14.29. The enrichment of LREE is obvious in the surface sediments. Correlation analysis results show that REEs tend to be concentrated in clay components; the intensive artificial breeding and fishing activities in this area lead to the reduction in the content of REEs in the surface sediment; the chondrites-normalized REEs distribution pattern show different degrees of positive La and Gd anomalies; the positive Gd anomalies are influenced mainly by coal combustion, while the La anomalies are mainly related to the contribution of coal and fertilizer. Through the combination of Pearson correlation, chondrite standardization, and (La/Yb)_N-(La/Sm)_N-(Gd/Yb)_N ternary diagram, it is concluded that the REEs in the surface sediments of the study area are related to human activities (coal burning and chemical fertilizers). The study provides a reference basis for the source control of pollutants and the ecological treatment of coal mine environment.